In the Diagram Below, Which Layer Is Able to Flow

Multiple Choice

In the diagram below, which layer is able to flow rather than being brittle?

A) 1 because water helps lubricate it
B) 2 because the rocks are of a different composition than in the other layers
C) 1, 2, and 3 because it is not under as much pressure as 4
D) 4 because it is under so much more pressure than 1, 2, and 3